A hybrid electric vehicle uses both an internal combustion engine and a battery power source. The hybrid electric vehicle efficiently combines the torque of the internal combustion engine and the torque of a motor.
Hybrid electric vehicles may be categorized as either a hard type or a mild type according to a power sharing ratio between the engine and the motor. In the case of the mild type of hybrid electric vehicle (or a mild hybrid electric vehicle), a mild hybrid starter & generator (MHSG) configured to start the engine or generate electricity according to an output of the engine is used instead of an alternator. In the case of the hard type of hybrid electric vehicle, a driving motor for generating driving torque is used in addition to an integrated starter & generator (ISG) configured to start the engine or generate electricity.
The mild hybrid electric vehicle does not provide a driving mode in which torque of the MHSG is used for the main driving torque, but the MHSG may assist the torque of the engine according to the running state of the vehicle and may charge a battery (e.g., a 48 V battery) through regenerative braking. Accordingly, the fuel efficiency of the mild hybrid electric vehicle may be improved.
A vehicle may include an auxiliary system that operates by receiving rotational power of an engine. The auxiliary system includes a generator (or an alternator), a compressor for an air conditioner, a hydraulic device, and a water pump.
The rotational power of the engine is transmitted from a crankshaft to the auxiliary system by a belt. The auxiliary system includes a pulley for receiving rotational power from the belt.
The belt wound on the pulley tends to be integrated into one, so that the length of the belt has been increased in order to drive the auxiliary system by one belt. Therefore, it has become important to keep the tension of the belt appropriately for smooth transfer of the rotational power.
In order to properly maintain the tension of the belt, a belt tensioner is used. There are various types of belt tensioners such as a mechanical type and a hydraulic type.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention, and therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.